Test handlers are used in the semiconductor industry for testing electronic devices, such as light-emitting electronic or photonics devices, in the form of light-emitting diodes (“LEDs”), integrated circuits and semiconductor chips. It is necessary to position the electronic devices in a desired orientation before subjecting the electronic devices to testing by a tester.
In some automatic test handlers which receive electronic devices such as LEDs from a bowl feeder for testing, the orientations of the LEDs are determined using a sensor at a linear track portion of the bowl feeder as they are being conveyed from the bowl feeder to a turret handler. The LEDs that are found to have the correct orientation are indexed to the next station of the turret handler. Those found not to have the correct orientation are rejected and returned to the bowl feeder. Statistically, about half of the LEDs will be rejected at the linear track since there is almost an equal chance of an LED being correctly or incorrectly oriented, thus reducing the feed rate of the LEDs to an equivalent extent.
Another common method of correctly orienting LEDs involves checking the electrical polarity of the LEDs. A bowl feeder will feed the LEDs to a turret pick arm. The LEDs are then pressed down at a test station where the electrical polarities of the LEDs are checked for their orientation. After checking the orientations of the LEDs, the turret pick arm will move up and index to an orientation correction station where the LEDs are pressed down onto the orientation correction station for polarity correction if necessary. Thereafter, the LEDs are again picked up and held by the turret pick arm, indexed and placed at a turret table to undergo optical and/or electrical testing. This method of sorting and correcting the orientation of the LEDs involves a number of pick-and-place steps. Furthermore, checking the electrical polarity is not useful for some electronic devices, such as dual dice LEDs, where the electrical polarity of the LED is similar irrespective of its orientation.